Best Vehicle Seat Position For Driving

Picture from the European Spine Journal

The laundry (towels, bed covers, pillowcases) in our clinics get picked up twice a week for the past 16 years by a husband and wife team - Ray and Elaine. Elaine does the driving while Ray does the pickup and delivery of the huge laundry bags. I spoke to them and Elaine was complaining about her back pain after all that driving and I told her it's probably linked to her lumbar (lower back) load from all the driving and sitting in their van.

Picture from the European Spine Journal

A recently published study used a Christophy spine model (inclusive of head, neck and limbs, pictured above) and compared calculated lower back loads and muscle forces while driving to experimental data from previous studies. 

Using data from previous radiology studies, this Christophy spine model was tested in different driving positions with different back supports. The load on the lower back was then calculated with the various back supports and backrest inclination angles.

0 cm, 2 cm and 4 cm lumbar supports were used along with inclinations of the backrest from 23 degrees to 33 degrees (by 2 degrees intervals).  

Ready for the results? Especially for those of you who drive a lot.

The overall lower back spinal loads and muscular forces at the L3-L4, L4-L5 and L5-S1 decreased very obviously with the 4 cm back support, with the seat inclination angle set to 10 degrees. With the 4 cm back support, the overall lower back spinal load decreased by 11.3 percent while  muscular forces were reduced by 26.24 percent.

The recommended backrest inclination angles are between 29 to 33 degrees with a 10 degrees seat cushion to the horizontal. 

This is a useful study to explain the association of drivers' sitting postion and the change in lower back load. It helps provide a reference for the prevention of low back pain.

Now if someone can send these recommendations to car manufacturers to improve the design of vehicle seats, that would be great.

References

Christophy M,  Faruk Senan NA, Lotz JC et al (2012). A Musculoskeletal Model For the Lumbar Spine. Biomech Model Mechanobiol. 11: 19-34. DOI: 10.1007/s10237-011-0290-6

Gao K, Du J, Ding R et al (2023). Lumbar Spinal Loads And Lumbar Muscle Forces Evaluation With Various Lumbar Supports And Backrest Inclination Angles In Driving Posture. Eur Spine J. 32: 408-419. DOI: 10.1007/s00586-022-07446-x.